1. Field of the Invention
The present invention relates to a form fill and seal method and apparatus wherein two sheets of web are brought together at the fill tube and sealed to each other at their respective edges to form bags, typically reclosable plastic bags.
2. Description of the Prior Art
The prior art regarding form fill and seal methods and apparatus, including vertical form fill and seal method and apparatus, is well-established in the prior art. Some prior art in this area includes U.S. Pat. No. 6,178,722 entitled “Application system for Sliders at Form-Fill-Seal Machine” issued on Jan. 30, 2001 to McMahon; U.S. Pat. No. 4,894,975 entitled “Method and Apparatus for Making Reclosable Bags with Fastener Strips in a Form Fill and Seal Machine” issued on Jan. 23, 1990 to Steven Ausnit; U.S. Pat. No. 5,951,453 entitled “Reclosable Bag Assembly and Method of Making Same”, issued on Sep. 14, 1999 to Yeager and U.S. Pat. No. 6,270,257 entitled “Reclosable Bag with Profile Strip Fastener Assembly Having Improved Opening Feature”, issued on Aug. 7, 2001 to Yeager.
Additionally, horizontal form fill and seal methods and apparatus, wherein separate sheets are used for the top and bottom of a container, are disclosed in U.S. Pat. No. 6,138,439 entitled “Methods of Making Slide-Zippered Reclosable Packages on Horizontal Form-Fill-Seal Machines”, issued on Oct. 31, 2000 to McMahon.
While this prior art has proven to be well-suited to the objectives of the industry, it is desired to further improve the methods and apparatus in this field.
It is always desirous to increase production rates and to reduce the complexities involved in the proper registration of the web in a high-speed device.
In particular, it is desired to reduce the angle of curvature imposed upon a single sheet of web as it is brought around the fill tube by the forming collar in vertical form fill and seal apparatus. This reduction in angle of curvature simplifies the proper registration of the web.
Additionally, in some applications, in may be desirous to form two bags simultaneously which increases production rates without increasing the linear speed at which a sheet of web is fed to the fill tube and the forming collar.